A conventional ECG system typically consists of between 3 and 10 electrodes placed on areas of a patient's body to detect electrical activity. The electrodes are connected to an ECG monitor by a commensurate number of wires/cables. A conventional ECG electrode typically comprises a resistive sensor element which is placed directly against the patient's skin. A number of electrodes are placed against the patient's skin to detect the electrical characteristics of the heart (e.g. the current through or voltage across the resistive sensor element) at desired vantage points on the patient's body. The detected signals are relayed through the wires to the ECG monitor, which is typically located on a lab table or the like, away from the patient's body. A signal processing unit within the ECG monitor processes the signals to generate an ECG waveform which can be displayed on a display of the ECG monitor.
FIGS. 1 and 2 show three electrodes 10, 12, 14 arranged in the so-called Einthoven's triangle on a patient's body 16. As is known in the art, electrodes 10, 12 and 14 may be respectively referred to as the Right Arm (RA), Left Arm (LA) and Left Leg (LL) electrodes because of the locations that they are commonly placed on body 16. To generate an ECG signal, various potential differences are determined between the signals from electrodes 10, 12, 14. These potential differences are referred to as “leads”. Leads have polarity and associated directionality. The common leads associated with the Einthoven's triangle shown in FIGS. 1 and 2 include: lead I (where the signal from RA electrode 10 is subtracted from the signal from LA electrode 12); lead II (where the signal from RA electrode 10 is subtracted from the signal from LL electrode 14); and lead III (where the signal from LA electrode 12 is subtracted from the signal from LL electrode 14). In addition to the leads shown in FIG. 2, other common leads associated with the Einthoven's triangle configuration include: the AVR lead (where one half of the sum of the signals from LA and LL electrodes 12, 14 is subtracted from the signal for RA electrode 10); the AVL lead (where one half of the sum of the signals from RA and LL electrodes 10, 14 is subtracted from the signal for LA electrode 12); and the AVF lead (where one half of the sum of the signals from RA and LA electrodes 10, 12 is subtracted from the signal for LL electrode 14). As is known in the art, the AVR lead is oriented generally orthogonally to lead III, the AVL lead is oriented generally orthogonally to lead II and the AVF lead is oriented generally orthogonally to lead I. The signals from each of these leads can be used to produce an ECG waveform 18 as shown in FIG. 3. Additional sensors can be added to provide different leads which may be used to obtain different views of the heart activity. For example, as is well known in the art, sensors for precordial leads V1, V2, V3, V4, V5, V6 may be added and such precordial leads may be determined to obtain the so-called 12lead ECG.
Some issues with traditional ECG technology make it an impediment for use, particularly in emergency response situations. The multiple electrodes and their corresponding wires may require extensive time to set up which may be critical in emergency circumstances. Having to maneuver around and detangle a large number of wires can be a nuisance. Multiple electrodes and wires can make it difficult to move a patient or administer medical aid to a patient. Signal noise from movement of the wires and wire tension can also degrade the quality of the ECG reading. Multiple wires can be particularly problematic during cardiac monitoring, where the ECG wires are attached to a patient for a long time. These issues with traditional ECG technology are exacerbated where there is a significant distance between the patient and the ECG monitor (i.e. where the electrode wires are long).
In addition to the problems with wires, current ECG systems use contact electrodes with resistive sensor elements. Such contact electrodes must be placed in direct contact with the patient's skin to obtain accurate signals. Typically, these contact electrodes are stuck to the patient's skin using an adhesive. The use of contact electrodes can be problematic in some circumstances. By way of non-limiting example, it may be undesirable or difficult to remove the patient's clothing in certain situations—e.g. where the patient may have privacy concerns, where the patient is suspected of having a spinal cord injury and/or the like. As another example, the patient may have a condition which makes it undesirable or difficult to apply current-sensing electrodes to the skin—e.g. the patient is suffering from burns to their skin, the patient has body hair which must be removed prior to using the contact electrodes, the patient is allergic to the adhesive and/or the like.
There is a general desire for improved ECG systems. By way of non-limiting example, there is a general desire for an ECG system that can provide greater flexibility for use by medical professionals in a variety of different circumstances, such as might be the case for emergency response technicians (EMTs). There is a general desire for ECG systems that may be more convenient and/or simple to use than existing ECG systems.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.